MPI global data

[dbm]

Good day all!

I am to communicate two S7 300 CPUs via MPI and I wish to accomplish this using MPI global data. So what I did was setup the GD table and compile & save the configuration done in NetPro. I tried to simulate it in PLCSIM, downloading both programs in two PLCSIM projects and then download the system data from NetPro, but no results were observed. Am I missing something here? Are there other important steps in the configuration process that I forgot to do?

In the attached screenshot of the NetPro configuration, do I still have to fill out the table boxed in red? If so, what could I be possibly missing in the configuration? Everytime I try to make a connection a pop up states that No valid connection could be established.

 

[JesperMP]

Have you followed the instructions in this FAQ:
https://support.industry.siemens.com/cs/ww/en/view/38726591

I dont know for sure, but I suspect that communications via MPI cannot be simulated.
As you can see in the FAQ, it is not all communication posibilities that can be simulated.

Apart from that, if this is a new project I recommend to stay away from MPI.
MPI is a dying standard, any PLC projects today should include Ethernet. If you chose an IM151-8 CPU it will even be quite inexpensive.

edit: Regarding the NetPro configuration, then you cannot setup connections via MPI in NetPro.
To communicate via MPI you must use X_PUT and X_GET, rather than PUT and GET.

 

[dbm]

It was actually from that FAQ that I got the idea to try and simulate the configuration. I wasn't aware at first that two PLCSIM could be used.

Would it be safe to try it out without prior testing? I am limited to using MPI communication since the existing CPU for which I would be communicating with is only capable of MPI communication.

Could anyone give some pointers on how to set up SFCs such as X_PUT,X_GET, etc. I'm really having trouble setting the parameters for these functions. Like in X_GET, what do you mean by VAR_ADDR and RD? In the example I saw the address for both parameters (VAR_ADDR and RD) are the same. Sorry I'm quite new in handling communication blocks so I'm having a hard time setting parameters.

Thank you for the feedback. Hoping to learn more about this

 

[JesperMP]

VAR_ADDR is an ANY pointer that points to the address in the partner CPU.
SD and RD are an ANY pointers that points to the addresses in the local CPU.

An example of an ANY pointer:
P#DB10.DBX20.0 BYTE 32
points to 32 Bytes, starting at DB10.DBX20.0

It is described if you hit F1 when having marked the blocks X_PUT or X_GET.